Yes, it is possible to install the spring backwards. If it unhooks there is something wrong. That would indicate expanding rather than contracting. Do you have the shop manual? Read it, the information is invaluable. If you are like me, after reading through the manual you realize how much you don't know. Get a Motors manual, buy an asembly manual, read them, as they are all great reference books. That is the very most basic information you can have. Even after installation you need to fine tune the spring.
